Oxide Ion Polarizability Research Articles

Optical properties of lead-tellurite glasses doped with samarium trioxide

The optical properties of a new family of xSm2O3-(40-x)PbO-60TeO2 glasses are investigated. The optical absorption spectra were recorded at room temperature in the UV-visible region. From the absorption edge studies, the values of optical bandgap energies have been evaluated. The refractive index, molar refraction and polarizability of oxide ions have been calculated by using Lorentz-Lorentz relations. The non-linear variations of the above optical parameters are discussed with respect to samarium concentration.

Thermo‐Optic Properties and Electronic Polarizability in Alkali Tellurite Glasses

The refractive indices (n) and densities (ρ) of xLi2O–(100−x)TeO2 glasses with x=15–30 and xNa2O–(100−x)TeO2 glasses with x=10–20 are measured in the temperature range of 30°–150°C in order to clarify thermo‐optic coefficients (dn/dT) and the temperature dependence of the electronic polarizability of oxide ions ( ) and optical basicity (Λ). It is found that the values of n, , and Λ increase almost linearly with increasing temperature. The values of dn/dT are around 7 × 10−5 K−1 and tend to decrease with increasing alkali content (Li2O, Na2O). In contrast, the values of d/dT and dΛ/dT are almost constant, irrespective of the alkali content. It is suggested that electronic polarizability has an important contribution on thermo‐optic coefficients, but the contribution of volume thermal expansion on thermo‐optic coefficients cannot be ignored. In the analyses of electronic polarizabilities of alkali tellurite glasses, the concept of group optical basicity for TeO3 and TeO4 structural units is also applied. It is explained that large thermo‐optic coefficients in Li2O–TeO2 and Na2O–TeO2 glasses are composed of oxides having small average single bond strengths and large optical basicities.

Optical and electronic polarizability investigation of Nd 3+-doped soda-lime silicate glasses

This paper reports on different physical and optical properties of Nd 3+-doped soda-lime silicate glass. The glasses containing Nd 3+ in (65− x)SiO 2:25Na 2O:10CaO: xNd 2O 3 (where x=0.0–5.0 mol%) have been prepared by the melt-quenching method. In order to understand the role of Nd 2O 3 in these glasses the density, molar volume, refractive index and optical absorption were investigated. The results show that the density and molar volume of the glasses increase with an increase in Nd 2O 3 concentration and consequently generate more non-bridging oxygen (NBOs) into glass matrix. The optical absorption spectra were measured in the wavelength range from 300 to 700 nm and the optical band gaps were determined. It was found that the optical band gap decreases with an increase in Nd 2O 3 concentration. On the basis of the measured values of density and refractive index, the Nd 3+ ion concentration in glasses, the polarizability of oxide ions and optical basicity were theoretically determined.

Optical Properties of the SiO<sub>2</sub>-Na<sub>2</sub>O-CaO-Nd<sub>2</sub>O<sub>3</sub> Glasses

Problem statement: This study researched on different physical and optical properties of Nd3+ doped soda-lime-silicate glass. The glasses containing Nd3+ in (65-x) SiO2: 25Na2O: 10CaO: xNd2O3 (where x = 0.0-5.0 mol%) had been prepared by melt-quenching method. The density and molar volume increase with increasing of Nd2O3 concentration due to increasing of Non Bridging Oxygens (NBOs) in glass matrix. Approach: The optical spectra were measured and evaluated their optical band gap and found to decrease with increasing of Nd2O3 concentration. Results: Moreover, these results showed that the refractive index of glass does not only depend on the density but also depend on the electronic polarizability of the glass. Conclusion: The values of polarizability of oxide ions, theoretical optical basicity were also determined.

Optical Investigation and Electronic Polarizability of Nd3+ Doped Soda-Lime-Silicate Glasses

Problem statement: This study researched on different physical and optical properties of Nd3+ doped soda-lime-silicate glass. The glasses containing Nd3+ in (65-x)SiO2: 25Na2O: 10CaO: xNd2O3 (where x = 0.0-5.0 mol%) had been prepared by melt-quenching method. The density and molar volume increase with increasing of Nd2O3 concentration due to increasing of Non Bridging Oxygen (NBOs) in glass matrix. The optical spectra were measured and evaluated their optical band gap and found to decrease with increasing of Nd2O3 concentration. Moreover, these results showed that the refractive index of glass does not only depend on the density but also depend on the electronic polarizability of the glass. The values of polarizability of oxide ions, theoretical optical basicity were also determined. Approach: This study investigated the effect of Nd2O3 content on optical band gap, density, molar volume, optical basicity and polarizability in soda-lime silicate glass. Series of Nd3+ doped soda-lime silicate glasses (in mol%): (65-x)SiO2-25Na2O-10CaO-xNd2O3 (x = 1-5 mol%) were prepared by the normal melt-quenching technique. Analytical reagent grade chemicals of SiO2, Na2O, CaO and Nd2O3 were used in the glasses preparation. Each batch of chemical was powdered finely and mixed thoroughly in porcelain crucibles and was later melted in an electrical muffle furnace for 3 h, at 1200°C. After complete melting, the homogenized melt was quickly poured onto a stainless steel mould that was heated at 500°C to form the glasses. The glass blocks thus resulted were immediately transferred to the annealing furnace that and were annealed at 500°C for 3 h and then slowly cooled down to the room temperature in order to remove possible thermal stains in the glasses. Finally, the as-prepared glass samples were cut and then finely polished to a thickness of 3 mm. The glass densities were measured by using xylene as an immersion liquid based on the Archimedes's principle. Glass refractive indices were measured at room temperature using an Abbe refractometer (ATAGO) and mono-bromonaphthalene as an adhesive coating. The optical absorption spectra of Nd3+ doped soda-lime silicate glasses were recorded at room temperature using a UV-VIS spectrophotometer (Hitachi, U-1800), working in 300-700 nm. Results: By addition of Nd2O3 into the SiO2-Na2O-CaO glass network, the density increases with increase in Nd2O3 content. The molar volume of the glass systems under study increases with increase in Nd2O3 content, which is attributed to increase in the number of Non Bridging Oxygen (NBOs). The optical band gap slightly decreases with the increase of Nd2O3 and results in the increase of bonding defect and non-bridging oxygen. The optical basicity of the glasses are increasing with Nd2O3 content change with the increasing of polarizability and consequently the increase in refractive index. Conclusion: The study of SiO2-Na2O-10CaO-Nd2O3 glass systems showed that the density and refractive index increase with increasing concentration of Nd2O3. The increase of molar volume with Nd2O3 content indicates that the extension of glass network is due to the increase of the number of NBOs. The optical band gap slightly decreases with in Nd2O3 content due to an increase in the degree of localization of electrons thereby increase of the donor center in the glass matrix. The electronic polarizability and optical basicity increase with the increase of mol% of Nd2O3, which is in agreement with the decrease of optical band gap. Moreover, the results found in this study show that the refractive index of glass does not only depend on the density but also depend on the electronic polarizability of the glass.

Influence of SiO 2 on the structure and optical properties of lithium bismuth silicate glasses

Bismuth silicate glasses containing lithium oxide with composition 20Li 2O·(80 − x)Bi 2O 3· xSiO 2 (5 ⩽ x ⩽ 70 mol%) have been prepared by melt-quench technique. Density ( D), molar volume ( V M) and glass transition temperature ( T g) for all the glass samples have been measured. FTIR spectroscopy has been employed to investigate the structure of these glasses in order to obtain information about the competitive role of Bi 2O 3 and SiO 2 in the formation of glass network. The increase of SiO 2 content in the glass matrix results in increasing the Si–O–Si bond angle and hence the ionicity of Si–O bond increases with decrease in Bi 2O 3/SiO 2 ratio. The optical transmittance spectra of all the glasses have been recorded in the wavelength range 200–3300 nm. The values of optical band gap ( E g) have been determined from the cutoff wavelength of these glasses. The average electronic polarizability of oxide ion ( α o 2 - ) and the optical basicity ( Λ th) have been estimated from the calculated values of the E g and were found to be dependent directly on Bi 2O 3/SiO 2 ratio. The variation in different physical parameters such as D, V M and T g and optical parameters; viz., E g, α o 2 - , Λ th with Bi 2O 3/SiO 2 ratio have been analyzed and discussed in terms of change in the glass structure.

PHYSICAL AND OPTICAL POLARIZABILITY AND TRANSPORT PROPERTIES OF BISMUTHATE GLASSES

Bismuth-based glasses containing ZnO , B 2 O 3 and Li 2 O are investigated through different physical, polarizability and transport properties. Raman spectroscopy reveals that these glasses are built from [ BiO 3] and [ BiO 6] units. Zinc in tetrahedral form is also observed. Density and glass transition temperature increase with the bismuth content. The refractive index, oxide ion polarizability and optical basicity also increase with the Bi 2 O 3 content, whereas the interaction parameter decreases. The DC electrical conductivity increases and the activation energy decreases with the increase in the Li 2 O content.

Physical and optical properties of Bi2O3-B2O3 glasses

Bismuth borate glasses with composition xBi2O3-(100-x) B2O3 (where x is in mol %, ranging from 25 to 50 in steps of 5) have been prepared using conventional melt quenching technique. The physical parameters like molar volume, oxygen packing density and optical basicity have been evaluated from the measured values of density. It is found that density, molar volume and optical basicity increases where as oxygen packing density decreases with increase of bismuth content. The optical absorption studies revealed that the cutoff wavelength increases while optical band gap energy (Eopt) and Urbach energy (ΔE) decreases with increase of Bi2O3 content. The Eopt values of these glasses are found to be in the range 3.338 to 3.025 eV where as the values of ΔE lies in the range 0.467 to 0.237 eV. Using Eopt values the oxide ion polarizability values have been evaluated. The values of optical basicity evaluated using oxide ion polarizability αo2- (Eopt) obtained from optical band gap are in agreement with those values calculated from optical basicity values of the constituent oxides.

Temperature dependence of refractive index and electronic polarizability of KNbGeO5 glass and its nanocrystallized glasses

The refractive indices (n) and densities (ρ) of a glass and transparent nanocrystallized glasses with the composition of 25K2O-25Nb2O5–50GeO2 (i.e., KNbGeO5) are measured in the temperature range of 30–150 °C in order to clarify the temperature dependences of the electronic polarizability of oxide ions (αO2−) and optical basicity (Λ). It is found that the values of n, αO2−, and Λ increase almost linearly with increasing temperature, and the values of the temperature dependence of these properties, i.e., dn/dT, dαO2−/dT, and dΛ/dT, tend to decrease slightly due to the nanocrystallization. It is clarified that the temperature dependence of the electronic polarizability of oxide ions in the precursor glass and nanocrystallized glasses has a large contribution for the temperature dependence of the refractive index in comparison with the contribution of density (volume thermal expansion). The features in the temperature dependences of αO2− and Λ in the present glass system is related to the large optical basicities of the constituent oxides of K2O, Nb2O5, and GeO2.

Effect of Bi2O3 on physical, optical and structural studies of ZnO–Bi2O3–B2O3 glasses

Zinc bismuth borate glasses with composition 10ZnO– x Bi 2 O 3 –(90 − x )B 2 O 3 (where x is in mol%, ranging from 25 to 50 in steps of 5) have been prepared using conventional melt quenching technique. Differential scanning calorimetry (DSC) studies showed that the glass transition temperature ( T g ) decreases from 473 °C to 449 °C as the content of Bi 2 O 3 increases. The optical absorption studies revealed that the cutoff wavelength increases while optical band gap energy ( E opt ) and Urbach energy (Δ E ) decreases with increase of Bi 2 O 3 content. The E opt values of these glasses are found to be in the range 3.464–3.169 eV where as the values of Δ E lies in the range 0.503–0.178 eV. The DSC and optical absorption studies revealed that the glass network becomes less tightly packed and degree of disorder increases with increase in Bi 2 O 3 concentration in the present glass system. The IR studies indicate that these glasses are made up of [BiO 6 ], [BO 3 ] and [BO 4 ] basic structural units. The values of optical basicity evaluated using oxide ion polarizability α b 2 − ( E opt ) obtained from optical band gap are in agreement with those values calculated from optical basicity values of the constituent oxides.

Effect of Bi<sub>2</sub>O<sub>3</sub> Content on the Properties of Bi<sub>2</sub>O<sub>3</sub>-BaO-B<sub>2</sub>O<sub>3</sub> Glass System

Glasses with composition xBi2O3:(60-x)BaO:40B2O3 with 10£x£50 (in mol%) have been prepared using the normal melt-quench technique. The optical absorption spectra of the glasses have been recorded in the wavelength range 400-700 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap are decreased with the addition of Bi2O3. The density and molar volume studies indicated that Bi2O3 in these glasses is acting partly as network modifier and partly as network former.Values of the theoretical optical basicity are also reported and discuss in term of oxide ion polarizability.

Optical properties of samarium doped zinc–phosphate glasses

Samarium doped zinc–phosphate glasses having composition Sm 2O 3 ( x )ZnO (60− x ) P 2O 5 (40) (where x=0.1–0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated. The values of density range from 3.34 to 3.87 gm/cm 3 and those of molar volume range from 27.62 to 31.80 cm −3. The optical absorbance studies were carried out on these glasses to measure their energy band gaps. The absorption spectra of these glasses were recorded in UV-visible region. No sharp edges were found in the optical spectra, which verifies the amorphous nature of these glasses. The optical band gap energies for these glasses were found to be in the range of 2.89–4.20 eV. The refractive index and polarizability of oxide ion have been calculated by using Lorentz–Lorentz relations. The values of refractive index range from 2.13 to 2.42 and those of polarizability of oxide ion range from 6.51×10 −24 to 7.80×10 −24 cm 3.

Electronic polarizability and optical basicity of lanthanide oxides

The average electronic polarizability of oxide ions α O 2 - in p- and s-block, d transition metal and heavy s- and p-block oxides has been calculated by Duffy and Dimitrov. However, lanthanide oxides have not yet been well revealed, which are promising materials for luminescence and nonlinear optical. In this study, new data of the average electronic oxide polarizability of rare earth oxides have been calculated on the basis of linear refractive index n 0 and energy gap E g. The optical basicity Λ of rare earth oxides has been estimated on the basis of average electronic oxide polarizability calculated from the refractive index n 0 and the energy gap E g. Our present conclusion suggests that lanthanide oxide should be supplemented to the second group according to the values of their oxide polarizability. We also looked for another lanthanide contraction phenomenon that the electronic polarizability of oxide ion decreases with increasing atomic number. Furthermore, close correlations are investigated among α O 2 - , Λ, E g , and n 0 in this paper.

Optical properties of samarium doped zinc-tellurite glasses

Glasses with the composition, (Sm2 O 3) x (ZnO)(40-x)(TeO 2)(60), were prepared by conventional melt quenching method. The density, molar volume, and optical energy band gap of these glasses have been measured. The refractive index, molar refraction and polarizability of oxide ion have been calculated by using Lorentz-Lorentz relations. Optical absorption spectra of these glasses were recorded in the range 300–700 nm at room temperature. The oxide ion polarizabilities deduced from two different quantities, viz. refractive index and optical energy band gap, agree well compared with other glasses. The nonlinear variation of the above optical parameters with respect to samarium dopant has been explained.

Classification of oxide glasses: A polarizability approach

A classification of binary oxide glasses has been proposed taking into account the values obtained on their refractive index-based oxide ion polarizability α O2−( n 0), optical basicity Λ( n 0), metallization criterion M( n 0), interaction parameter A( n 0), and ion's effective charges as well as O1 s and metal binding energies determined by XPS. Four groups of oxide glasses have been established: glasses formed by two glass-forming acidic oxides; glasses formed by glass-forming acidic oxide and modifier's basic oxide; glasses formed by glass-forming acidic and conditional glass-forming basic oxide; glasses formed by two basic oxides. The role of electronic ion polarizability in chemical bonding of oxide glasses has been also estimated. Good agreement has been found with the previous results concerning classification of simple oxides. The results obtained probably provide good basis for prediction of type of bonding in oxide glasses on the basis of refractive index as well as for prediction of new nonlinear optical materials.

Classification of Simple Oxides: A Polarizability Approach

A simple oxide classification has been proposed on the basis of correlation between electronic polarizabilities of the ions and their binding energies determined by XPS. Three groups of oxides have been considered taking into account the values obtained on refractive-index- or energy-gap-based oxide ion polarizability, cation polarizability, optical basicity, O 1s binding energy, metal (or nonmetal) binding energy, and Yamashita–Kurosawa's interaction parameter of the oxides. The group of semicovalent predominantly acidic oxides includes BeO, B2O3, P2O5, SiO2, Al2O3, GeO2, and Ga2O3 with low oxide ion polarizability, high O 1s binding energy, low cation polarizability, high metal (or nonmetal) outermost binding energy, comparatively low optical basicity, and strong interionic interaction, leading to the formation of strong covalent bonds. Some main group oxides so-called ionic or basic such as CaO, In2O3, SnO2, and TeO2 and most transition metal oxides show relatively high oxide ion polarizability, O 1s binding energy in a very narrow medium range, high cation polarizability, and low metal (or nonmetal) binding energy. Their optical basicity varies in a narrow range and it is close to that of CaO. The group of very ionic or very basic oxides includes CdO, SrO, and BaO as well as PbO, Sb2O3, and Bi2O3, which possess very high oxide ion polarizability, low O 1s binding energy, very high cation polarizability, and very low metal (or nonmetal) binding energy. Their optical basicity is higher than that of CaO and the interionic interaction is very weak, giving rise to the formation of very ionic chemical bonds.

Polarizability, Optical Basicity and O 1s Binding Energy of Simple Oxides.

A suitable relationship between oxide ion polarizability, cation polarizability, optical basicity and O1s binding energy in XPS spectra has been searched on the basis of experimental and calculated data reported in the literature for numerous simple oxides. It has been established that O1s binding energy decreases with increasing oxide ion polarizability, cation polarizability and optical basicity. The observed O1s chemical shift to lower binding energy from 533.5eV to 528.2eV could be explained with an increase in electron charge density of the oxide ions, due to an increase in their electronic polarizability. Increased oxide ion polarizability means stronger electron donor ability of the oxide ions and vice versa. That is why O1s binding energy can be used for the construction of common basicity scale of different amorphous and crystalline materials. On this basis the simple oxides have been separated into three groups according to the values of their oxide ion polarizability, optical basicity and O1s binding energy.